The invention relates to a headrest adjusting arrangement, particularly of a rear headrest in a motor vehicle, having a headrest pivot bearing unit that is fixed at the seat. At this headrest pivot bearing unit, two head pad holding devices are disposed that are spaced away from one another in the direction of the pivotal axis.
Rear headrests represent an important accident protection for the passengers in the rear seats. However, when the rear seats are unoccupied, the rear headrests represent an impairment of the driver's view toward the rear that in principle can be avoided. Both aspects are taken into account by the rear headrest adjusting arrangement of this type. Up to now, this headrest adjusting arrangement was operated manually. The disadvantage in this case is that for reasons of convenience, the headrest is often not swivelled into the correct position.
It is an objective of the invention to provide a motor-operable rear headrest arrangement of a simple construction in which the driving unit requires only little installation space.
This objective is achieved according to preferred embodiments of the invention by the fact that a pivot bearing shaft is provided having two connecting parts for the holding devices spaced away from another and connected with the pivot bearing shaft in a torsionally fixed way, that adjacent to the pivot bearing shaft, a driving motor is provided having a motor shaft that is parallel with respect to its axis to the pivot bearing shaft, and that a gearbox is provided that connects the motor shaft with the pivot bearing shaft.
According to the invention, the driving motor, together with the gearbox, finds space between the two connecting parts for the holding hoops. The driving motor that is oblong in the direction of its motor shaft extends in parallel with respect to the axis next to the pivot bearing shaft so that the cross-sectional dimensions of the required installation space in a plane that is vertical or perpendicular with respect to the pivot bearing shaft axis are comparatively small. The whole pivot bearing unit with the pivot bearing shaft, the driving motor and the gearbox therefore easily find room in the possibly toroidally elevated area of the rear window shelf between its front edge and the head pad receiving trough that at least partially receives the head pad in its inoperative position. Without any special measures, the motor-driven rear headrest adjustment arrangement can therefore be installed instead of the manual rear headrest adjusting arrangement, or, if necessary, may be exchanged subsequently for the latter. The preferably one-piece gear shaft drives both holding hoops simultaneously. The mechanical construction is therefore reliable with respect to its operation.
In a preferred further development of the invention, it is provided that the gearbox comprises a gear shaft having a worm segment into which a motor worm engages that, in a torsionally fixed way, is connected with the motor shaft, and having a worm segment which engages in a worm wheel element that, in a torsionally fixed way, is connected with the pivot bearing shaft. Thus, the driving motor is connected with the pivot bearing shaft via two individual worm wheel gears with the advantage of a correspondingly high step-down ratio which permits the use of a cost-effective fast-running driving motor of small dimensions and low weight.
In a particularly preferred manner, the worm wheel element is developed in a sector shape. The required pivoting angle for the headrest adjustment that in general is below 180.degree. permits the reduction of the worm wheel element to a sector-shaped worm wheel element. Particularly advantageous is the resulting further reduction of the required installation space.
It is also suggested according to certain preferred embodiments that the pivot bearing shaft have a non-circular cross-section, preferably without rotational symmetry. This facilitates the assembly and, if necessary, the disassembly of the pivot bearing unit for purposes of repair because the connecting parts as well as the worm wheel element that are provided with a passage opening corresponding to the cross-section of the pivot bearing shaft, must only be pushed onto the pivot bearing shaft. When a square shaft with a rotational symmetry of 90.degree. is used, for example, the possibility exists in principle that the elements to be pushed on may be pushed onto the shaft in correspondingly four different rotating positions. In order to exclude this during the mounting, it is suggested in certain preferred embodiments that the pivot bearing shaft have a cross-section without rotational symmetry. Particularly preferred is a pivot bearing shaft in the shape of a star shaped cross-section. A one-sided flattening of this star shaped cross-section will eliminate the rotational symmetry.
In a further development of certain preferred embodiments of the invention, it is suggested that the pivot bearing shaft, at least at one end, is pivotally disposed in a bearing bush which, in turn, is inserted into a bearing opening of a bearing plate, in which case the bearing plate has a bearing bush insertion opening that leads into the bearing opening in a direction that is essentially perpendicular with respect to the pivot shaft axis. These measures permit an easy assembly, and, if necessary, disassembly of the pivot bearing shaft. In this case, it is preferably provided that the bearing bush has a circular section that is adapted to the circular bearing opening and has flattened areas that are opposite one another, in which case, the distance of the flattened areas from one another corresponds essentially to the width of the insertion opening. The mounting therefore takes place by rotating the bearing bush by about 90.degree. after the insertion through the insertion opening into the bearing opening.
It is suggested in certain preferred embodiments that a pivot bearing housing be provided, essentially in the shape of a hoop that is oblong in the direction of the pivot bearing shaft. The ends of this hoop are bent in the same direction for forming the bearing plates. In this case, it may be provided that the hoop is equipped with at least one laterally projecting fastening tab for the gear carrying the driving motor. The pivot bearing housing that is formed in this way may be formed by a corresponding sheet metal stamping which has compact dimensions, mechanically is sufficiently stable and requires low manufacturing costs.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.